Ice tray



June 11, 1940. G1, L NG 2,203,915

ICE TRAY Original Filed Feb. 26, 1937 INVENTOR. v Gsak: A. 0M5:

HIS ATTORNEYS.

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Patented June 11, 1940 PATENT OFFICE- ICE TRAY George It. Long, Dayton, Ohio, asslgnor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application February 26,1937, Serial No. 121,927

- Renewed'November 7, 1939 4Clalms. (o1. 62-1085) Thisinvention relates to refrigerators and! particularly to freezing devices employed in mechanically refrigerated household refrigerator cabinets.

In order to obtain fast freezing of a substance to be frozen in the evaporator of a household refrigerator cabinet it has been customary to employ an ice tray and grid structure therefor both of which are constructed of or formed from metal. Because of inherent characteristics of water to adhere to metal surfaces the separation 'of ice blocks from such trays and grids has presented many problems. The metal of such trays and grids are ordinarily somewhat porous or pitted throughout the surfaces thereof with which water contacts during freezing and such surfaces tend to cause the water to spread over and adhere to the metal. The water upon being frozen in contact with these metal surfaces sticks 0 or bonds to the metal. My invention is directed to the provision of surfaces of metal ice trays,

molecules upon contacting a tray and grid walls to thus prevent bonding the ice thereto.

An object of my invention is to provide an improved ice tray and grid structure .therefor so as to facilitate the removal of ice blocks there- Another object of my invention is to coat the walls of a metal tray and grid structure therefor with a waxy substance to thereby render the walls water repellent to prevent bonding of ice thereto.

In carrying out the foregoing objects it is a still further and more specific object of my invention to provide a substantially permanent wax coat on the walls of a metal tray and grid structure therefor which coat consists of a mixture of carnauba wax and a micro-crystalline mineral wax having a melting point of the order. of 175 F.

Further objects and advantages of the present invention will be apparent from the following description, reference being had tothe accompanying drawing, wherein a preferredform of the present invention are clearly shown.

In the drawing: I

Fig. 1 is a top plan view of an ice tray and a 50 grid structure positioned in the tray having my invention embodied therein;

Fig. 2 is a longitudinal vertical sectional view of the tray and grid disclosed in Fig. 1 and taken on the line 22 thereof; and

55 Fig. 3 is an enlarged sectional view of one of the webs of the grid structure illustrating a coating applied thereover in accordance with the invention.

Referring to the drawing, for illustrating my invention, I have shown in Figs. 1 and 2 a metal ice tray l0 having upstanding and outwardly converging walls ll defining a relatively shallow pan-like member adapted to receive a removable metal grid structure or mold member I2. The metal tray in and grid or mold l2, employed to divide the interior of the tray into a plurality of ice block compartments, may be of any desired form or construction but are preferably constructed in accordance with the tray and grid structure disclosed in the copending application of Donald H. Reeves, Serial No. 98,213 filed Aug. 27, 1936. The grid structure in the present disclosure therefore comprises a plurality of transverse walls N that are movable relative to a longitudinal wall l5 by movement of a lever i6 pivotally attached to the grid to break the ice blocks or cubes [1, frozen in the tray and grid, first from the tray l0 and thence from the grid structure l2, after separating the grid together with ice adhering thereto from the tray as fully described in the copending application referred to. It is the primary purpose of my invention to improve the construction and facilitate the operation of removing ice blocks or cubes from a tray grid structure particularly of the type disclosed in the foregoing identified copending Reeves application.

The tray l0 and walls I and I5 of grid l2 of the present disclosure are formed from or constructed of sheet aluminum since this material is of light weight, strong and a good conductor of heat. It has been found that this material will, in the course of extended use, oxidize, corrode and become tarnishedor'discolored and therefore the wallsurfaces of the grid are treated to eliminate as far as possible such discoloring due to oxidization and corrosion. The tray l0 and grid or mold I! are therefore treated in a manner which causes the formation of an aluminum oxide and/0r hydrate coat on the exposed wall surfaces thereof and which coat resists discoloring and tarnishing and is pleasing in appearance. The method of coating the wall surfaces of the tray and grid is known to those skilled in the art as an anodical treatment or anodizing process and is atpres'ent being widely carried out commercially, therefore no further detailed description of this method is believed necessary herein. It is well known that this anodical or anodizing treatment of ice trays and grids provides a surface on the aluminum which is relatively porous, pitted and rough. Thus by treating the aluminum trays and grids in the manner described these trays and grids are provided with wall surfaces that can be readily impregnated, or coated with a suitable substance that will destroy or eliminate the porosity or roughness of the surfaces and render these wall surfaces water repellent.

Others have, prior to my invention, endeavored to improve and facilitate removal of ice blocks from metal tray or grid walls by plating and highly polishing these walls. It is true that the plating and high polish of tray and grid. walls has destroyed their porosityand roughness but these walls have not necessarily been rendered water repellent by the plating thereof and consequently water or ice will bond thereto. Thus plating and polishing of the tray and grid walls does not materially facilitate the operation of removing ice blocks therefrom.

My invention is specifically directed to the provision of a wax coating on metal ice tray and grid walls, and particularly tray and grid walls anodized as hereinbefore described, that will be substantially permanent in water repellent characteristics to thereby facilitate removal of ice therefrom. A coating of carnauba wax, which is amorphous and melts at a temperature between 175" and 195 F., applied to the walls of ice trays and grids has been found to render the walls water repellent and this coatingis relatively permanent during extendedoperations of removing ice therefrom.- However, since this wax is of a vegetable, origin, diflicult to obtain and,

in addition imported into this country, it's use in a pure or undiluted state is too costly for application to trays or grids on a productive basis.

Since the use of carnauba wax alone for coating trays and grids is prohibitive it is desired to employ another wax, possessing characteristics somewhat similar to the characteristics of car-.

'n'au'ba wax, to dilute and mix with the carnauba wax for' reducing the 'cost of the coating material to thereby render the application of a wax mixture containing carnauba to-ice trays or grids practical as to quantity production.

Ihave discoyered'that a wax which is a by product of crude oil, obtained from the mass of waxes that are left in the oil after distilling ofl gasoline and kerosene therefrom, and which is micro-crystalline in form and'of a considerably higher melting point as compared to parafiin is suitable for mixing with carnauba wax for my purpose. This mineral wax is plentiful, of low cost and is clearly distinguishable from paraffin by having a finer crystalline structure and having a melting point of approximately 50 higher than paraffin. In actual tests this mineral wax hasbeen found to melt at a temperature of from 170? to 180 F. as compared to the melting point of from 120 to 130 F. for most grades of paraflin. Ordinarily this mineral wax is mixed with carnauba wax in the production of automobile,-

furniture and floor polishing waxes and is employed therein to dilute and soften same so that the polishing wax can be readily worked and more easily applied to surfaces to be polished.

This mineral wax also contains water repellent providing an effective water repellent coating on articles. I have found that in addition to reducing the cost of the coating material the mixobjects of my invention than a coating consisting of carnauba wax alone. i a My invention therefore resides in the provision of a coating on metal surfaces of ice trays and grids which comprises a mixture of a microcrystalline mineral wax and carnauba wax. This wax mixture: applied to the metal walls of an ice tray or grid forms a smooth coating thereover and facilitates removal of ice blocks therefrom due to the water repellent characteristics thereof. It is knownthat a mixture of carnauba wax and paraflin will produce a water repellent coating for ice trays and grid structures but it is believed that the larger crystalline characteristics of paraflin in this mixture prevents the mixture from adhering permanently to the metal because such a coating is quickly broken down and is therefore removed little by little from metal tray or grid walls to thus become ineffective' for its intended purpose. However, by employing a micro-crystalline mineral wax of the type herein disclosed for mixing with carnauba wax the entire mixture is of a, substantially amorphous nature and is not as readily broken down or removed from the tray and grid walls. A coating consisting of 50% carnauba wax and 50% of the micro-crystalline mineral wax has been found to remain on metal ice tray and grid walls indefinitely and throughout many operations of removing ice blocks from the tray and grid. While this 50-50 mixture coating has been found to be highly satisfactory it is to be underderstood that mixtures consisting of from 50% to 75% of the mineral wax and from 50% to 25% of carnauba wax will provide a substantially permanent water repellent coating for theimetal walls of trays and grid structures and will greatly facilitate the removal of ice therefrom. Obviously the melting point of the mixtures will vary in accordance with the percentage of the two waxes employed therein.

I have illustrated. in Fig. 3 of the drawing the metal grid or mold wall It having an aluminum oxide or hydrate coat formed or provided therethat the entire grid structure and the tray is to be provided with the wax coating I9. This wax coating I9 preferably consists of, 25% carnauba wax and 75% of the micro-crystalline mineral wax which has a melting point of the order of 175 F. It is to be understood that I do not wish to be limited to the specific proportions of the two wax constituents of the. wax coat l9 referred to for the reason that other proportions of thewax have been found to be satisfactory. The substantially amorphous wax coating I9 is relatively permanent and is water repellent therefore water will not adhere thereto during freez- -ing thereof and the ice will not become bonded to the grid walls. Obviously therefore the operation of moving certain of the grid walls relative to certain other walls thereof, duringthe act of removing ice blocks from the grid structure', in

the manner fully disclosed in the copending Reeves application hereinbefore referred to, is greatly facilitated. By eliminating bonding of ice-blocks to the grid walls less force is necessary to actuate the ice removing lever and deformation of these walls is prevented to thereby permit the walls to be constructed of relatively thin sheet V aluminum.

I will now describe one method of applying the wax coat I! to the tray III or to grid I! in order to carry out my invention. The substantially amorphous wax, consisting of any desired proportion of the micro-crystalline mineral wax and carnauba wax, is melted in a suitable container at a temperature dependent upon the proportions of the wax in the mixture. The tray and grid, which have previously been anodized,

'to be coated with the wax is submerged in the molten wax and permitted to remain therein for approximately ten minutes to insure that all parts thereof are thoroughly coated. The molten oven and reheated to a suitable temperature to cause the wax to flowto thereby remove any excess wax therefrom while the desired amount clings or adheres to the tray or grid walls in the form of a thin film thereover. This thin film of wax is both in and on the anodized coating on the tray or grid. If desired the tray or grid may be rotated or whirled to throw off excess wax during reheating of the wax. The tray or grid may, if desired, be heated by hot air forced thereover under pressure to remove excess wax therefrom. While I have described one method of applying the wax coat to a tray or grid structure it is to be understood that-other methods may be adopted in carrying out the objects of my invention.

It will be apparent from the foregoing that I have provided an improved ice tray or grid or both in that I have rendered the .water contacting surfaces thereof repellent to water to thereby prevent bonding of ice thereto. My improved tray and grid greatly facilitates the operation of removing ice blocks therefrom and permits the structures to be constructed of relatively thin metal because the force necessary to cause separation of ice from the tray or grid is minimized. I wish it to be clearly understood that by dcscribing the mineral wax in the present dis closure as a niirco-crystalline or substantially amorphous wax having a melting point of the order of'175". F. I thereby distinguish this wax from paraffin which is ;also .a mineral wax but which has a more distinct and definite crystalline form andja substantially lowermelting point. 1

;:While the'form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A freezing device for refrigerating systems comprising a metallic tray adapted to contain a substance to be congealed or frozen and having a substantially permanent water repellent wax coating over at least the surfaces thereof to be contacted by the substance, said coating including a mixture of carnauba wax and a substantial- 1y micro-crystalline mineral wax having a melting point of the order of 175 F. as distinguished from paraffin and capable of repeated cleansing in liquid at a temperature of from to F.

2. A freezing device for refrigerating systems comprising a metallic tray adapted to contain a substance to be congealed or frozen and a metallic grid structure disposed therein and dividing the interior thereof into a plurality of compartments, said tray and said grid structure each having a substantially permanent water repellent wax coating over at least the surfaces thereof to be contacted by the substance tobe congealed or frozen, said coating including a mixture of carnauba wax and a substantially micro-crystalline mineral wax having a melting point of the order of F. as distinguished from paraffin and capable of repeated cleansing in liquid at a temperature of from 140to 170 F.

3. A freezing devicefor refrigerating systems comprising a metallic grid structure for disposition in a tray adapted to contain a substance to be congealed or frozen to thereby divide them-- terior of the tray into a plurality of compartments, said grid structure having a substantial ly perminent water repellent wax coating over at least the surfaces thereof'to be contacted by the substance to be congealed or frozen, said coating including .a mixture of carnauba wax and a substantially micro-crystalline mineral wax having a melting point of the order of 175 F. as distinguished from paraflin and capable of repeated cleansing in liquid at a temperature of from 1'40 to 170 F. l

4. A freezing device for refrigerating systems comprising a metallic tray member adapted to contain a substance to be congealed or frozen and a metallic grid member disposed in the tray and dividing the interior thereof into a plurality of compartments, one of said members having a thereof to be contacted by thesubstance, said coating consisting of a mixture of from 50% to 25% carnauba wax and from 50% to 15% of a substantially micro-crystalline mineral wax as distinguished from paraflin and having approx-'- GEORGE R. LONG.

- water repellent coating over the metal surfaces 

